Method of forming hollow or tubular articles of irregular shape.



Patented Feb. ll, I902.

, J. P. 'SNEOOON. METHOD OF FORMING HOLLOW OR TUBULAR ARTICLES OFIRREGULAR SHAPE.

(Application filed Apr. 12, 1901.)

2 Sheets-Sheet l.

{U0 Model.)

fl L6 36 ll/l/ lllj/ ill;

v ffzorneya.

THE Noams PEIERS 00.. momma, WASHINGTON, n. a

No. 693,172. Patented Feb. ll,' I902.

J. P. SNEDDON.

METHOD OF FORMING HOLLOW 0R TUBULAR ARTICLES OF IRREGULAR SHAPE.

A (Applicutionfiled Apr. 12, 1901; (No Model.) 2 Sheets-Sheet 2.

": fli g" m: mums PETERS c0. wumoumn. WASHINGTON, n. c.

UNITED STATES PATENT OEFIcE.

JAMES P. SNEDDON, OF BARBERTON, OHIO, ASSIGNOR, BY MESNE ASSIGN MENTS,TO THE STIRLING COMPANY, OF JERSEY CITY, NEW JERSEY, A

CORPORATION OF NEYV JERSEY.

METHOD OF FORMING HOLLOW 0R TUBULAR ARTICLES 0F IRREGULAR SHAPE.

SPECIFICATION forming part of Letters Patent No. 693,172, dated February1 1, 1902.

Application filed April 12, 1901. Serial- No. 55,540. (No specimens.)

To ctZZ whom it may concern.-

Be it known that 1, JAMES P. SNEDDON, a resident of Barberton, in thecounty of Summit and State of Ohio, have invented a new and usefulImprovement in Methods of Forming Hollow or Tubular Articles ofIrregular Shape; and I do, hereby declare the follow ing to be a full,clear, and exact description thereof.

My invention relates to a method of forming hollow or tubular metalarticles of irregularoutline, such as serpentine boiler-headers, bottomblow-off connections for boilers, or otherarticles.

Serpentine boiler headers and similar articles are made fromcomparatively heavy metal, and as such articles are irregular in shapeconsiderable difficulty has been experienced in forming such articles ofwroughtiron or steel. By reason of the thickness of the metal composingsuch articles it requires heavy pressure to properly shape the same, andin orer to prevent the collapsing of the tube during the shaping processit is necesi sary to use'an' internal support or mandrel for the same.By reason of the great irregularity in the shape ofthese articlesdifficulty has been experienced in providing a suitable internal supportor mandrel which will offer suificient resistance to the action of theexternal forging or pressing dies and which, nevertheless, is capable ofbeing withdrawn or removed from the header or other article after thesame is shaped. Heretofore ser- 3 5 pentine headers and similar articleshave been made of wrought metal only by the use of complicated sectionalmandrels, which were inserted in the tube and thereafter withdrawn.

The object of my invention is to provide a method of forming sucharticles in which this difficulty is overcome; and to this end itcomprises the formation of such articles by inclosing. or incasing atubular blank having closed ends in suitable dies and then subjectingsaid blank to internal pressure, which will force the tubular blank outagainst the walls of the incasin g dies and be shaped thereby, and inthe specific embodiment of myinvention the blank is heated before beinginclosed in the dies, and the internal pressure is secured by compressedair, which is first admitted to the tubular blank at the desired orpossible pressure and which is then further compressed by means ofhydraulic pressure.

In the accompanying drawings I have shown suitable apparatus forcarrying out my method, and in said drawings- Figure 1 is a plan view ofthe apparatus, the die being shown in section. Fig. 2 is a verticalsection on the line 2 2, Fig. 1. Fig. 3 is a Vertical transversesectional view of modified forms of dies for inclosing the tubularblank. Fig. 4 is a side view of a shaped serpentine boiler-header. Fig.5 is a sectional View illustrating the formation of a bottom blow-offconnection for boilers, and Fig. 6 is a sectional View of the finishedbottom blowofi connection.

In the drawings, 1 represents the dies for in closing orincasing thetubular blank 2, said blank having its ends suitably closed, as by thecap-nuts 3 3, and one end being connected by the pipe 4: to the upperend of the receiving-tank 5, which is mounted upon the supports 6. Tothe lower end of said tank 5 is connected a pipe 7, which is providedwith the coupling 8 and with an ordinary valve or cook 9 at its lowerend. To the coupling 8 is secured a pipe 10,whichleads to the hydraulicaccumulator 11, and said pipe is provided with a cut-off valve 12. Theaccumulator 11 is of the ordinary form and-is provided with the chamber13, with the lower end of which the pipe 10 communicates, and whichchamber is supplied with suitable water pressure through the pipe 14,which is connected to suitable hydraulicpumps. (Not shown.) In thechamber 13 works the plunger 15, which is suitably weighted, as at 16,at its upper end,said plunger working water-tight through the upper endof the cylinder 13, a suitable gland 17 and packing 18 being providedfor that purpose. The accumulator is of a type very commonly used, andfurther details of description are not necessary.

19 represents an air-compressor of any suit able type, which isconnected by the pipe 20 to a coupling 21 in the pipe 10, although saidpipe 20 may lead directly to the receivingtank 5, if desired. In thepipe 20 a suitable cut-off valve 22 is provided. The dies 1 comprise thestationary lower die 23 and the removable upper die 24, suitable means,such as the pins 25 and keys 26., being provided for holding the upperdie 24 firmly in place. The interior faces of these dies are so shapedas to give the desired form to the article to be made.

In the practice of my invention the tubularblank 2, which is shown ascircular, but may be given a preliminary shape approximating its finalshape, if desired, is placed in the dies 1, either in the cold state orfirst having been raised to a proper temperature, and the dies 1 arefirmly closed, so as to incase or inclose the tubular blank. Compressedair from the compressor 19 is then admitted to the interior of the tubeup to a pressure from one hundred to two thousand pounds per squareinch, as the case may be, depending upon the thickness of the metalforming the tubular blank. When the tube is filled with air at thedesired pressure, the valve 22 in the pipe 20, leading from thecompressor is closed and the valve 12 in the accumulator-main 10 isopened. The water-pressure in the accumulator further compresses the airin the receiving-tank 5 and in the tubular blank in the dies 1 to suchpressure as may be required to force the metal of the tubular blank outagainst the Walls of the dies to conform to the shape of the latter. Thewater. from the accumulator 11 by reason of its greater specific gravitywill not rise above the air in the receiving-tank 5, but will force theair upward and into the tubular blank and will compress the air to apressure equal to that in the accumulator. The direct pressure of theair is of course limited by the clearance-spaces in the compressor, and,furthermore, air is a highlycompressible body, so that by means of thesame it is not possible to secure sufficient pressure to force a tubularblank having thick walls out against the walls of the inclosing dies;but water being an incompressible body by means of the accumulator avery high pressure can be secured,which pressureis communicated tothe-air in the tubular blank and will force the walls of the same outagainst the inclosin g dies. By reason of the fact that articles made ofheavy metal must be heated before they are shaped it is not desirable tointroduce the water directly into the heated tubular blank in the dies,for the reason that the water would chill the said blank so rapidly thatit'would prevent the proper shaping of the same. Air, on the contrary,hasa verylow heat-absorbing capacity, and consequently it will notseriously reduce the heat of the blank in the dies. It will therefore beobserved that by first filling the heated blank with the compressed airand maintaining a sufficient quantity or reservoir of air in thereceiving-tank to prevent the water entering the tubular blank and thencompressing this air by means of hydraulic pressure I am enabled tosecure in the tubular blank an unyielding pressure equal to the pressurein the accumulator, but in such a manner that the heat of the blank isnot reduced thereby. It is therefore necessary in the particularapparatus shown that the pipe 4 should lead from the upper end of thereceiving-tank 5, and it is also necessary that the accumulator beconnected to the lower end of said tank, so as to provide a largequantity or reservoir of air between the water column and the compressedair in the tubular blank in order that the water may not rise highenough to enter said pipe 4. While I have shown the aircompressor asconnected to the coupling 21 in the accumulator-main 10, this is notnecessary, as the air-pressure may be introduced directly into the tank5 and at any point therein, it not being necessary to introduce it intothe lower end of the tank, as shown. After the blank is suitablycompressed the valve 12 is closed and the valve 9 opened to allow thewater and compressed air to escape. The finished blank will then beremoved from the dies and another blank put in place therein, with itsends suitably closed and coupled to the pipe 4, when the operation willbe repeated.

In some cases it maybe found desirable to make the inclosing diesmovable, and such arrangement is shown in Fig. 3, wherein 28 representsa stationary die having the sinuous horizontal face 29 and plainvertical face 30, and 31 represents a movable plain-faced side die and32 a movable sinuous-faced top die. The dies 31 and 32 may be moved byordinary hydraulic cylinders, (not shown,) and in the use of such diesthe blank is inclosed loosely in the same, and after the tubular blankis filled with compressed air the movable dies may be moved up closer tothe blank and compress the same to some extent, and these dies may begiven slight inward and outward movements during the time that thepressure is applied to the interior of the blank in order to properlyforge and shape a the article.

The dies shown in Figs. 1, 2, and 3 are adapted to form the serpentineboiler-header shown in Fig. 4, said header, as is well-known, havingplain side faces, which are substantially parallel to each other, andthe opposing two faces being sinuous or serpentine in ends of theseswells or protuberances are out 01f to form the connecting-openings 3637, (shown in Fig. 6,) and the opening 33 is closed by a screw-plug 38.

While it is not absolutely necessary that the tubular blank should firstbe heated, still in forming articles whose walls are composed of metalof considerable thickness this will be found to be necessary; but inshaping the lighter forms of articles the blank may advantageously beworked cold. The blank may also be given any preliminary shapeapproximating its final form as found desirable or necessary; but myinvention is not intended to be limited in any of these particulars.

The apparatus herein shown and described is not claimed in thisapplication, but is claimed in an application of even date herewith,Serial No. 55,539.

What I claim, and desire to secure by LettersPatent, is

1. The method of shaping hollow or tubular metal articles which consistsin inclosing a hollow blank in suitable clies subjecting the sameinteriorly to air at the desired pressure,

and then further compressing said air by hydraulic pressure applieddirectly against said compressed air.

2. The method of shaping hollow metal articles which consists in heatinga hollow or tubular blank, inclosing the same in suitable dies,subjecting the'same interiorly to air at the desired pressure, and thenfurther compressing said air by hydraulic pressure ap* plied directlyagainst said compressed air.

3. The method of shaping hollow metal articles which consists ininclosing a hollow blank in suitable dies, subjecting the sameinteriorly to compressed air at the desired pressure, and then furthercompressing said air by hydraulic pressure applied directly against saidcompressed air, the said blank being subjected to external pressuresimultaneous with the internal pressure.

In testimony whereof I, the said JAMES P. SNEDDON, have hereunto set myhand.

JAS. P. SNEDDON.

Witnesses:

O. D. EVERHARD, E. E. BAKER.

